Myth: Partial DID is the same as OSDD

Similar names, different systems

People often discover that one clinician says “OSDD,” another says “partial DID,” and someone online insists they are the same thing. The confusion usually comes from mixing two different diagnostic systems.¹²

The diagnostic system matters

The DSM-5-TR includes DID and other specified dissociative disorder (OSDD). ICD-11 includes DID, partial DID, other specified dissociative disorder, and unspecified dissociative disorder.¹² The same person could receive different labels depending on which system a clinician is using and which criteria best describe the presentation.

For quick reference, each code below links directly to the relevant WHO ICD-11 documentation.¹

ICD-11 diagnosis	Reference code
Dissociative identity disorder	6B64
Partial dissociative identity disorder	6B65
Other specified dissociative disorder	6B6Y
Unspecified dissociative disorder	6B6Z

Where partial DID fits

Partial DID is an ICD-11 diagnosis, not another name for OSDD. ICD-11 created it for presentations that resemble DID but do not meet the full ICD-11 criteria in a particular way.³

In his clinical explainer, Mike Lloyd describes DID and OSDD as separate “buckets.” Where ICD-11 is available, he places partial DID between them rather than treating it as a duplicate of OSDD.⁴

Although the name can sound like a measure of severity, “partial” refers to how the diagnostic criteria are met, not how much a person is suffering.³

OSDD and unspecified disorder are doing different jobs

OSDD is used when dissociative symptoms cause significant distress or impairment but do not fit the criteria for another named dissociative disorder.⁵² That is not the same clinical job as partial DID, even though the terms can overlap in everyday conversation.

Unspecified dissociative disorder is used when there is not enough information to make a more specific diagnosis. “Unspecified” describes what the clinician knows at that point. It does not automatically say anything about how serious the symptoms are.⁶

The question a clinician is trying to answer

The important question is not which label sounds closest. It is which diagnostic criteria best describe the person's presentation within the system being used. Sorting that out requires the same careful assessment as any other dissociative diagnosis.⁷⁸

Footnotes

1. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative disorders. Dissociative disorders overview. ICD-11 grouping and structure for dissociative disorder categories. ↩ ↩² ↩³

2. International Society for the Study of Trauma and Dissociation. (2026). Fact Sheet IV – What are the Dissociative Disorders? DID and OSDD clinical definitions. ISSTD overview differentiating DID, OSDD, and related dissociative categories. ↩ ↩² ↩³

3. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Partial dissociative identity disorder. Code 6B65. ICD-11 intermediate code for partial dissociative identity disorder. ↩ ↩²

4. Lloyd, M. (2025). Partial DID or OSDD: Classifying and diagnosing types of dissociation. 03:21, 06:42. Video explanation of DID and OSDD boundaries and partial DID as an intermediate formulation. ↩

5. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Other specified dissociative disorder. Code 6B6Y. ICD-11 category used when dissociative symptoms are impairing but not fully covered by another specific code. ↩

6. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Unspecified dissociative disorder. Code 6B6Z. ICD-11 unspecified code used when a specific diagnosis cannot be established. ↩

7. International Society for the Study of Trauma and Dissociation. (2011). Guidelines for treating dissociative identity disorder in adults, third revision. Journal of Trauma & Dissociation, 12(2), 115-187. pp. 128-130. Differential diagnosis and common sources of diagnostic confusion. ↩

8. World Health Organization. (2026). International Classification of Diseases 11th Revision (ICD-11), Dissociative identity disorder. Code 6B64. ICD-11 coding and diagnostic criteria family for DID. ↩